\begin{tikzpicture}
	\tkzDefPoints{0/0/O, 1.5/0/A, 1.1/1.5/B, 0/1.5/M}
	\tkzDrawSegments(O,A  O,B)
	\tkzDrawSegments[dashed](O,M)
	\tkzMarkRightAngle(M,O,A)
	\tkzLabelPoints[right](B)
	\tkzLabelPoints[below](A, O)
\end{tikzpicture}

